Spraying your prime coat indoors can be done easily and successfully. Your choice of sprayer is important. You want to purchase a HVLP (HVLP = High Volume / Low Pressure), Most modern HVLP sprayers have a very fine spray, which is ideal for painting walls. The owner of a Home Depot or other Lowes or other similar stores should be able to help you out - they are pretty knowledgeable. Make sure you use a proper mask, and a spray mask would be ideal. Make sure you have the best quality paint you can, often they will have a specialist paint at the store which is designed especially for spray painting. You can find the directions online here: