As anthonie said, search through the Nitdroid threads and go to the Nitdroid forum too

However, Android for the N900 should not be considered as a replacement OS, nor is it ready for the end user. The two big issues with Nitroid are poor power/battery management and NO Voice calling ability.

If you are not confident with using Xterm, then it might be best to not install Nitroid at all as even using the Auto installer will still require you to open the shell at some point.

If you do decide to go ahead, please read ALL and the whole of the previous threads as most problems you may have, will already be answered.

Welcome to TMO too