how can i make a call in X-Lite soft phone?

Question

with wich digits i have to start?

Answer 1

Right click and select "SIP Account Settings". Add an account (you'll need to know details such as Asterisk/SIP server). Once you've registered, you can dial a number by clicking the digits.

For details, check out the X-Lite user guide here:
http://www.xten.com/docs/X-Lite3.0_UserGuide.pdf