I’m depressed since I started high school and I don’t know how to deal with it

Ever since I started high school I became depressed since im really lonely and basically have no friends. Even if I try to make friends I’m just not confident at all since I’m really insecure about myself and I have low self esteem and it became more obvious when the first day at lunch I realized I had no one to sit with and I had no friends. I always sit alone at lunch and as soon as I finish eating I head and go to the restroom and stay there until lunch ends since I’m too embarrassed to sit alone. I just don’t know what to do I really need help I’m tired of feeling so lonely and having to be alone with no one to be with since while all the kids my age enjoy being with their friends and all that I’m in my room rotting in there just on my phone or in my PlayStation all day since I have nobody and by this point it’s has starting to affect since I feel so lonely