Each Brand of Phone have different way in Rooting. Some famous Brand can be done just by download an app like Kingo Root, Superuser, SuperSU, etc..
But for other Brand, that apps may not support. This is like dillema for us. All can we do is try to Search with google according to our phone type. Usually, manual Rooting is by use Flash Tool.
Be carefull of manual Rooting! We can Brick our phone if someting went wrong. So, back up system first before doing this. It's mpre convenient to backup with Recovery Tools like CWM or TWRP. So, we can Restore our phone even that our phone was brick.
Recovery tool analogue to Live CD in Windows OS. We can boot into our System even that our system is unbootable.