There is a lot of online education resources that can assist your learning of research methodology. And many of them are free to use. I am going to introduce only a few of them as example so that you know where to look.
Source 1: Websites of universities’ libraries
Many librarians are not just sitting behind the desk and wait for students or teachers to borrow books. They are making a lot of publicly accessible online resources on the libraries’ websites to educate people on how to do research. Here are some examples:
Source 2: MOOCs
MOOCs are massive open online courses that are free to take for anyone with internet and a digital device. Common platforms that offer good quality of courses from their partnering universities include: coursera, edx, udacity, futurelearn.
Source 3: Academic databases or publishers websites
Big academic publishers such as springer and Wiley have created dedicated pages for introducing research methodologies.
Source 4: Dedicated websites of research methodology