Suu Kyi, a Nobel Peace Prize laureate, spoke at the end of a three-day party congress in Yangon and which was attended by more than 900 delegates from around the country.
She is one of four women on the NLD's 15-member executive and among 120 elected members to the party's central committee, a BBC report said.
She urged party members to unite and move away from increasing infighting and factionalism.
"For the benefit of the country we should unite and get along," Suu Kyi said.
Suu Kyi, who will lead the party into the 2015 national election, also called for younger members to be allowed to "strengthen the party with new blood," the BBC report said.
"This congress is about choosing the right leaders who will serve both the future of our organization and our country," she said.
The NLD's internal elections were the first for the party, formed in 1988 and which won parliamentary elections in 1990.
But the military junta refused to recognize the elections and remained in power, continuing to harass and repress political parties and pro-democracy dissident groups.
Suu Ki, 67, spent most of the years in some form of incarceration, from jail to house arrest. She was barred from running as a candidate in the military's 2010 parliamentary general election -- the first multiparty general election in 20 years -- designed to move the country toward a civilian government and a more open society.
Suu Kyi was released from house arrest six days after the 2010 election.
The NLD boycotted the 2010 election, which was won by former Gen. Thein Sein, now Myanmar's president and who heads the National Unity Party consisting of many former junta leaders who resigned to run as civilians.
But last year the NLD won 43 seats out of 44 in by-elections, including one for Suu Kyi who sits in Parliament as the main opposition leader.
While the NLD remains a popular opposition to the government, it faces many challenges if it wants to capture the vote in 2015, especially among ethnic groups, many of whom are embroiled in military confrontation with the government in the jungles around the country's frontiers.
The congress and internal elections and appointments have been important for the NLD to show that it is moving with the fast changing political scene in Myanmar, once a pariah state but now wooed my many countries interested in business opportunities, including natural resource exploitation.
However, Suu Kyi said the NLD has acted undemocratically at times, with its central committee making decisions without consulting party members, a report by the Irrawaddy magazine said.
She said the NLD's conduct was because of restrictions imposed by the former military government, which also prevented the party from holding a congress.
Many of its leaders are in their 70's and 80's, while questions remain about the effectiveness of its lower- and mid-level organization, the Irrawaddy report said.
"We want someone who loves to take responsibilities, not positions," Suu Kyi said during the congress.
Suu Kyi's comments also bring into light her own 25-year leadership of the NLD, something the party might have to move away from to satisfy her call for new blood, Aung Thu Nyien, director of VAHU Development Institute in Chiang Mai, Thailand, said.
The NLD will have to include younger members who want more of a say on policy and to be in position of influence within the party, Thu told Radio Australia.
The party also must overcome a growing concern among minority groups, particularly in Rakine state, already a major issue for the central government of President Thein Sein, Thu said.
Myanmar, a Buddhist majority country, has its Muslim minority mostly in the northwestern Rakhine state, also is home to Rohingya, a Muslim group with close ties to neighboring Bangladesh.
Communal violence in May left nearly 80 people from both communities dead, mostly in Sittway, Maungtaw and Buthidaung townships. More than 100 people were injured and nearly 5,000 homes, 17 mosques, 15 monasteries and three schools were burned, the government said.
As Myanmar moves further toward a more open democratic society, the country's thousands of exiled democracy advocates and political dissidents are faced with the choice of remaining in exile or moving back.
"It's becoming difficult to find things to complain about," Aung Naing Oo, deputy director of the Vahu Development Institute, formed by Myanmar student activists who fled the country during unrest in the late 1980s. "Everyone is basically hoping that they can go back," he told The New York Times last month.
The increasing openness of Myanmar's government and society in general means fewer mainly Western governments, charities and non-government organizations are funding dissident exile groups.
Coupled with a drive by Myanmar government ministers to lure back dissidents -- a sort of reverse brain drain -- the raison d'etre for being in exile is evaporating slowly.
"Ultimately if you're an activist, you want to be where the action is," Naing told the Times. "If that action is not where you are, you have to move."
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