How to sideload apps on Nokia Lumia 521

[nitikosovo]

1.How to sideload apps on Nokia Lumia 521
Is there any limitation how many can be sideloaded at once *(have a limited number of apps that are sideloaded)
2.How to make my device developer unlocked for free!!

 

[pkcable]

Maybe this thread can help?

http://forums.windowscentral.com/windows-phone-8/252703-how-install-third-party-apps-wp8.html