Bdf reader, add path , for loop

Hi guys .I have a question about opening my bdf file. Actually i used bdf_reader but there are a lot of things that i got error.first of all, how can i add path a folder in order to not give 'specified file x.bdf does not exist in Matlab path' error.I should mentioned that i have many trials of my data and i put them into x folder. I don't know how to import them in matlab or adding them. And second , I have a problem with 'K' in for loop. What should i do? I really appreciate if anyone could help me . Thank you