hey i need help... in list box

i wana load List1
like idassword
txt1:txt2
then its working like when i click on the button
one id chek then agian i click on the button then other id chek
how can i?
anyone got idea

i mean when i click on the button id send to txt1 and password send to txt2 and one by one chek all id with button when i hit button one chek another time other same like tht all list..
thanks