How do I pull up carpet and what should I replace it with?

Here is how to pull up carpet.

https://www.familyhandyman.com/floor/carpet-repair/tips-for-removing-carpet/

Be careful around the perimeter with the tack strips.

What type of flooring do you want? Vinyl, hardwood, tile? If you want a "painted look" then you need to paint it. First it needs to be washed with TSP, let dry thoroughly. Then prime and finally painted with paint formulated for concrete. Any paint store will have what you need. Just know concrete floors are hard and cold.

In addition to Namoi's advice, I would wear heavy gloves and a face mask as the stuff will shed all the dirt. I would first vacuum up the loose dust, then mop it.... and I would use Floor Paint not concrete paint unless your sub-floor is concrete.

If the floor is wood it could possibly be refinished but if you still want to paint it you could also give it a pickled or white-washed look, then a few coats of water-based poly as that won't yellow like the oil-based. https://www.youtube.com/watch?v=6BotwiT8_Ys to get the wood natural you will have to rent a drum sander to remove the top layer of the wood. https://www.youtube.com/watch?v=mPzY9911MZM

Depends on whats,under yiur carpet. Once you remove your carpet, pad and tact strip reask the question telling us the surface material

How to proceed will be dictated by your subflooring and if the carpet was glued down.