HSA Advice / Guidance

I have a HSA account since 2019 that my old job provided to me which took about $50 per month from my month check. I left my old job this past March and stop putting money on to it. I recently learned that the money is supposed to be invested like ROTH IRA.

However I’m very unfamiliar with the index funds offered in a HSA. Is there are solid index that I should look into or invest in? Any advice/guidance would be greatly appreciated!