License requirements for racing ...
Racing in Belgium requires a UCI International Racing license as a foreign rider. If you country has UCI licenses but are very expensive due to insurance reasons you can also talk to a team here about getting a Belgian license, which is 150 euros the last time I checked. Also with a Belgian License you will be able to do Pro Kermesses races with the professional racers, but these races are quite fast and usually 180km’s. Be aware that the Belgian Federation is becoming stricter with foreign riders in regards to licensing, so you may run into problems.
You will also be requited to bring a "Foreign Permission Letter" from your federation. This is a letter of good standing that says you are free to race in Belgium (and seperate letters for other countries you might race in ... France, Holland, Germany would be the mostly likely). Be sure to bring this letter to every race as they are now asking for it every race these days.
Your first race in Belgium you will also be required to buy a Belgian Bar-code Card, which can be used in the years following; so keep it and bring it with you again. This card will speed up the registration process as you will only have to present the card (along with your federation letter and UCI License) to register at the next race.
A note for Juniors and all under 18's: On your first race you will be required to buy a Racing Card. This keeps track of the number of races you do while in Belgium. The Belgian Federation restricts the amount of races you are allowed to do in a week to just 3 races (and 50 races in a year in one disipline (road, track, cross) and 60 in total. You are also not allowed to race the day before a stage race and the 4 days after. There is also a restriction to the number of stage races you can do in a year. The week starts on Monday and ends on Sunday.
For 15-16 year olds there is a max of 2 races a week and restrictions on the total number of races a year. I don't suggest riders younger than 16 come to Belgium to race, but instead focus on developing in your country. If you do come to Belgium, do so on a short trip with a structured plan.