i just knowe how to use exprressions in parametre

A good place to start is with the expression cookbook. You can find this in the Houdini help.

Using the textport in hodini is also a must. Type exhelp in the textport to see all the default expressions. Use exhelp <command> to see the help for a particular expression. Use exhelp -k <search string> to search using key words. Note to omit the <>.

You can also use the expression editor to type in your expressions. With your cursor in the parameter field, hit alt-e. Gives you nice syntax highlighting.

Once you are familiar with the basics and have specific questions, ask away!