You might be better just putting the photos onto a USB stick, an SD card or CDR and taking them to any well known "high street" printer. Staff are usually helpful and knowledgeable and it probably works out a lot cheaper too.
If you want to do it yourself you can from within Windows (assuming that's what you use). Windows photo gallery has an option to crop pictures etc and size them to common paper sizes.
And yes glossy side up :)