My first cycling experience.

[cyberknight]

All i can add to the above is make sure your bike is set up right , many make the mistake when 1st starting to ride of having the saddle too low which makes it hard work on the thighs and tend to try and push a fast gear slowly rather than trying to spin a slightly easy gear a bit faster which puts less strain on the legs .
there are many bike fit guides , i found this one for flat bars but much of it applies to road bikes too
https://www.purecycles.com/blogs/bicycle-news/basic-bike-fit