Could and expert in computers tell me what do I need in order to have wireless in my apartment?

At this time I only have internet access by cable, and since it is a temporal apartment I not allowed to change the service

Could some one help me and tell me where could I found a computer store?

Media Markt at the station (SBB) and any Interdiscount are good starting points.

You need a wireless access point, but I'm not an IT specialist, so I'm sure someone with more authority in the matter will post soon.

I am not an expert in the slightest, but we've just bought a wireless kit from 'Interdiscount' and it works fine. Was pretty simple to set up. It's a little black box which gets connected into the little Cablecom box (or whoever your provider is) which then connnects into the wall. There are Interdiscount branches all over the place - you ccan heck for your nearest branch on-line under 'Filialsuche' on www.interdiscount.ch
Hope that helps!

Like the other poster said. Buy a router and follow the instructions which should essentially tell you to connect it to your cablecom modem and then either use your built in WLAN function on your laptop or insert the wireless dongle into your USB port on the PC and you're away. The only slightly sticky bit may come if/when you set up the security (i.e.password) but it isn't rocket science.

Have faith in your abilities and jump in!

(if you have any issues with the process just post more and someone will help - might even be me)