Ok
Double click your way into your BGI Save Folder:
My Computer --> Program Files --> Black Isle --> Baldur's Gate --> Save (or MPsave)
If you were playing a multiplayer game then you need to double click into your MPsave, if not open your Save folder instead..
Once you're in there, look for your most recent save file name (or just the one you want) -- right click on it, and choose "Copy" Then click your way into the BG II - SoA folder (use the method described above, and in the Black Isle folder just click on BG II instead of BGI. Once you're in your BGII folder, Double click on either the Save or MPSave folder. Once inside, right click and choose "Paste".
Once you've done that you'll be able to import from your character(s) from the save file.
If you want, you can also just copy your exported BG I character to the BG II character folder using the same method described above, you'll just be looking for the folder "Characters" instead of your Save (MPSave) folder.