I'm trying to setup a C152 profile, but I can't find anywhere needed data for fuel burn at the sea level, at the service ceiling and for a 500 fpm descent.

Can somebody help me, please?

Page 38 of your pdf (5-14) shows the fuel burn from 2000 ft - 12000 ft. For 12000 ft, I'd keep the worst of the values (5.3 gallon/hour), and plan with that.

On the next page (5-15), you can see that for SL, the range is practically the same as it is for 2000 ft. So the fuel consumption is somewhat the same too. If you want to get really detailed, you can try to guess based on that graph, or just take the 2000 ft values, adding a tiny bit if you want to plan safer.