Hi Matias, welcome.
If you are only balding on the crown, and you still have a viable natural hairline, that will make hair replacement very easy. You will only need a crown topper to cover your bald spot. Hair systems of that type have no visibly exposed edges, so once they are in place they are pretty much completely undetectable to sight without much effort.
You obviously need a good match of colour, texture and curl, so you will need to ask about that. The best way is to have a custom piece manufactured to a sample of your own hair, but if you have a fairly standard colour and texture an acceptable match with a stock unit may be available, which will be faster.
You may have a choice of base material - usually lace mesh or plastic film ("skin"). I am a fan of lace, because it is breathable, but that is less important if it is just a crown topper, and skin mimics human scalp better than lace, which is important if you are going for a low density look with a lot of scalp showing (the density obviously has to match the density of the surrounding natural hair).
If you are getting a custom piece you may choose to get a parting and/or a crown swirl.
You will also have to discuss what adhesives you are going to use. Usually with skin it will be glue of some sort. With lace it can be tape or glue. Tape is easier to apply and clean off afterwards, but glue is better for a result that is undetectable to the touch, if someone runs their hands through your hair - that may or may not be important to you.
Finally you will need to discuss maintenance. Is the salon going to do the maintenance for you, or will it educate you so that you can detach, maintain and reattach yourself? Each solution has its pros and cons, which we could discuss further if you like.
Hope that is useful.
Noah