I want to get custody of our grandkids and don't know where to start. We have them every thurs-sun and provide rides. They do not have jobs nor do they have a vehicle and there living arrangement is not good the parents both are mentally handicaped and they can't provide the proper parenting

I want to get custody of our grandkids and don't know where to start. ...

Start by seeing an attorney.

Generally, grandparents are rarely awarded custody as opposed to the parents. But it would depend on whichever state our country you are in.