Java around the world

i got a router linksys hook up to my main computer (computer1) . another computer (computer2) use wireless usb adapter air link 101. the computer2 always got connect to internet but sometime the lan work but sometime not. so sometime when i play lan game, it disconnects all the time. How am i gonna fix it. And when i try to connect to maincomputer from computer2 it needs username and password, but i didnt set up any account for it. so where can i find the username and password? also i cant connect my computer2 to the share printer. i have unabled sharing file and printer in computer1 and type in correct printer name but it keeps saying that window cannnot connect to the printer. Either the printer name was typed incrrectly, or the specified printer has lost is connection to the server. For more information, click help. Plz help me with these problems.