For adding mobile apps to Google Play Store you need to open Google Play Developer Account!
First of all, you need to signup from this link for create Google Play Developer Account, if you dont have gmail account you need to use this link before create developer account. but if you have you don't need!
After creating account then play developer account, you need pay for it! It is 25 $ for one time fee. And you can developer more than one apps with that! You don't need pay for one by one. Read and agree to the Google Play Developer distribution agreement and click to pay! For registration fee you can use visa and master cards.
After pay that one email come, and now you can fill the Google Play Developer Profile. In mercant center you can see the Tax profile, clearly you need read that and fill with right values. It is important to get pay back! From your apps sales.
Please not buying 2 accounts with same credit cards.
You are only have one account same time. If you are ban from developer program, other linked accounts banned too.
There is lots of rules for develop and publish mobile apps.
Don't forget the backup your key for your app, or use Google Play key system.
Good luck with sales!