Oven isn’t working

I am absolutely clueless and terrible when it comes to appliances.

We have a gas oven. It’s pretty old. At least 10 years, probably much older.

The burners on top work fine, but the oven won’t light/start and it smells like gas while its trying to start. It doesn’t smell like gas any other time or when its off.

Any ideas? Where do I start?