Click on the start-menu (the circle with the windows-logo on it) in the bottom-left of your screen. Two columns will appear. The second item just below the icon on the right-column opens your home folder. It is either named Administrator or has your Windows username. For me it is named "ms".
I have attached a screenshot to illustrate where to find your home-folder in the start-menu. Don't get confused by the German names there.

That folder contains more folders named "Desktop", "Downloads", "Documents", "Contacts" and a few more. In that folder you wil also find "AppData". Open that. There you will see Local, LocalLow and Roaming. Open "Roaming". Within that you will find "SecondLife" among (probably) a LOT of others. Open "SecondLife". And there you will finally find the "logs" folder which contains... surprise, surprise...

the log-files.