Methodologies and data collection help!

Good afternoon

I am in first year of my PhD in management studies and need to select an appropriate data collection and analysis method. My problem is that I can’t really understand the methodologies like grounded theory, phenomenology, thematic analysis etc.

What I have thought is to use a mixed method approach for data collection (qualitative + quantitative). For that, I am thinking about conducting semi-structured interviews with the key participants of my study. I settled for this as most of the researchers have used interviews and surveys as the means for data collection. I have also prepared the questionnaire but I am unable to get my head around the theoretical perspective. How will I analyse the qualitative data?

Any help regarding this matter would be greatly appreciated! Thank you!