My girlfriend is very Insecure about her appearance, I dont care about her looks

You can’t do that for her.

She needs to do it for herself.

Try to compliment her often - but don't overdue it. Stay honest so she can accept your compliments. Birdie

Well not caring how she looks is not a good thing you should tell her she is beautiful and maybe get her help and ask why she does not think is beautiful maybe there is something in her past. Maybe try standing in front of a mirror with her and ask her to look in the mirror are ask her what is wrong with her.

You can only be supportive and say and do nice things for her. One day she will love herself enough and believe your words.

Self-confidence is in the name. "Self." It's something she needs to come to on her own. What you can do though is repeat what you said here to her. That's she's beautiful. Don't need to make a big deal about. An out of the blue, "I'm so lucky to be with someone as beautiful as you" can carry a lot of weight. What you don't want to say is that you don't care about her looks. Go positive and make it about her.

You could just be supportive and agree with her

As someone who struggles with that myself i say be as supportive and positive as you can. At the end of the day you cant make her do anything she doesnt want to do. Do you know if she wants to change her thinking about herself?

Don't. It'll never work. It will bite you back for sure