The most of the team leaders I know were developers. You were a very good developer and management decides to promote you. If you are a good developer than you’ll be a good team leader (maybe 😄).
When you became team leader you are downgrading to Junior level. Because you should have more vastly skill set.
The very first thing to do is to know that you are not a coder any more! Write down this on sticker and look at it every day until you finally understand this.
Build new measurement system so you can decide how good you are. You should measure yourself by the results of your team.
How your team performs, what climate is in your team, how fast business gets what it wants, how users and your teammates are happy, how quick team grows their skills and much more…
More about this in later posts.