I was also going to mention DAVID: https://david.ncifcrf.gov/summary.jsp
You could start there, input your list of genes from each part of the analysis as separate lists, select Functional Annotation Clustering, and focus on Gene Ontology terms (the defaults are already selected) to start. This will produce terms with Benjamini Hochberg P values, I believe.
Ultimately, being a researcher is about taking control of a project and forming your own hypotheses and conclusions based on what your data is saying to you. Guidance is needed of course.
maybe you should consider a different profession?
The man who comes from undeveloped country to developed one for PhD, don't know about recent tools, techniques used in research. In the beginning assigned very difficult task, to write a paper from a research which done by another person. But i accept this task i am very near to it, please guide me further.
Given the information you provided, I'm not entirely clear how to help you. I'm not sure how to make gene ontology enrichment analysis suck less for you.
Could you please tell me one thing that, how to pick the most important cellular component ? What are the rules to pick it?
For example 1-cytoplasm- Observed 30 proteins. 2-intracellular part-Observed 23 proteins. 3-intracellular-Observed 20 proteins.
There is no such thing as 'most important'. Everything inside and outside the cell is important, it just depends what your question is.
That 1 protein in the cytoplasm might be responsible for lots of effects, if it's a transcriptional regulator for example, but it is just as important as the 30 proteins it might control, that actually have a phenotypic effect.
Sounds like you're too focused on the number of proteins that seem to be enriched, rather than what they do, and whether them being enriched in your test conditions makes any biological sense.
You will need to give a lot more information on your research questions and the analysis you performed, because giving advice in this setting is rather hard.