Quantitative signal analysis using the Welch method

Hi there,

I'm quite new to Matlab and need some help.

I want to perform a quantitative analysis on an EEG signal (.mat file, single matrix).

I don't want to use the pwelch() function, but do the implementation manually.

The conditions are as following: 4 sec. epochs, 50% overlapping, cosine window, fs=512 Hz;

Please give me a little help how to start or some helpful links.

Thanks, Jules