It is my first time writing an article on a software project. I am supposed to use ACM UbiComp paper format. I already have a structure that I should follow and there is a Background & Research Methods section after Abstract, Introduction, Related Work sections. I have browser through several articles, but some of them either dont have it, have only background section or have only research methods section. I am having hard time to find an article that has this section and moreover what I must write on here. My project is about Bluetooth location tracking and I do have the implementation and evaluation, so it is not something theoretical.
In your Introduction, you will have set out the problem your project is addressing; and in the Related Work section, you should have described similar projects that address slightly different problems, in particular highlighting why they don't address your problem. That provides the justification for why you worked on your project.
For the Background and Research Methods section, while the section title is a little inappropriate for a software development project, you need to describe the steps you took leading up to actually implementing your project. This may be complicated, because there's often an iterative process of trying something out and then revising it if it doesn't work out. Some of the things you could cover are:
The section should prepare the reader for the Implementation section, which should describe in detail the interesting parts of the implementation as a system. There may be some overlap with things you've already discussed in the previous section, so aim to cover each topic in detail in one section or the other, not both.
In summary, the section needs to cover all those things that were going on in your head in between formulating the problem you wanted to solve, and actually developing the implementation. You probably made some "aha!" realisations during that period that were critical to being able to complete the implementation -- you need to help other people understand those.