how do i convert a poi.gpi file to one that i can open to my garmin

Not Sure about posting a link for it so

Just type convert GPI to CSV in a search window and you will find some

Should already open on your Garmin

If you loaded the POI data correctly with Garmin's POI loader and saved it to SD or your Garmin, you should already be able to use the locations on your Garmin.

Where to?, Extras, Custom POIs

If you want them to show up automatically on routes, the icon (bmp), and voice (mp3) files have to have the same filename as that csv file. And for alerts you either need to include something in the filename, or use Manual mode of POI Loader to set speed or distance. You can have different sets of POIs in one poi.gpi, as long as the bmp and mp3 for each individual set match names (different sets can have different names).

nuvi 750, eTrex Legend HCx, Mobile 10/Palm TX, GPS 45