When you join up with online casinos you will have options when signing in, you may pick to play for real or as a guest player. When you opt for the guest player you will be taken to the same version of the casino as if you were playing for real but you will be in free mode. The only casino games you will not be allowed to play is the progressives as the jackpot goes up based on real money wagers. You will first need to download the casino then go through the sign up process.
After that you log in and go directly to the bank to add fun money. Some casinos will give you unlimited amounts of fun money to play with, which is pretty nice. From there you just go play the casino games and have fun. If you do find the games pretty interesting and decide you want to give them a try for real, then you might as well collect a no deposit bonus from some of the best casinos found on the net.
Personally I believe that playing at real casinos for fun is a better option than download free game apps or playing on popular game sites. Many of those have malware that will infect your computer as in free they do need to get something out of it. This is how they make money to provide the games however it really messes up a persons computer. So online casinos is a safer option without effecting how your computer will operate. Same with mobile devices they are being infected at a mass rate right now and users must be aware that this is happening and not only are they throwing ads at you but they are stealing information. So be careful and play only at trusted sites.