since putting a giffgaff sim in my phone, why won't my internet work?

[stopthenoise]

Everything else works but not the internet. I had a Tesco sim in it before and when I got the phone I set up a google account. When I put the giffgaff sim in it says account error and says my password is wrong. I tried to add another account but it says there's already an account on the phone. Also there's no 3G symbol to say there's any internet access. It's probably something really simple but i'm not very techy so any help is greatly apppreciated. I put the Tesco sim back in and internet works fine.

Giffgaff needs some internet setting put in manually.

if you go onto the forum and type your phone type and 'internet settings' into the search, there will be pages to show you what needs to be done and how.

Or you can just ask in the forum ans someone will link you to the right areas.

What make and model is it?You need to manually enter the Giffgagg APN settings,but I need the make and model before I can link as some models vary?

All sorted, thank you. Didn't realise you had to manually set it up Thanks again