How to compile source code in gentoo?

I have downloaded a file named emesene-r999.tar.gz which is a source code file and then I used the following command to decompress it:

tar xvfpz emesene-r999.tar.gz

Quesiton: I don't know how to compile it then!

It is highly appreciated if someone can help me solve this problem!

cd emesene*
善惡喜惡皆執著 到頭南坷一夢中

I have tried what you have suggested but it only generated an icon on the Desktop.
And I tried to double click this icon but no any response !
Anyway, thanks for your answer
入面通常有個 呢兩個 file,INSTALL 或/和 README…