It seems like you might need some basic Linux training. I suggest starting with the lessons at software carpentry. For now, however, I have a suggestion: why don't you try your task using Galaxy? I wrote the initial version of the SRA toolkit Galaxy integration that's now on the public server. You should be able to play around with your data now, while learning the Linux basics you need to go further with your analysis.
hi, there is a toolkit called sratoolkit. inside of it, there is a subtool called fastq-dump. once you install sratoolkit, go to the bin of sratoolkit folder, type "fastq-dump <accession number="">" and it puts the fastq format of that sra file to your current directory. could you share the source link of that specific sra? I couldnt find such sra in EBI SRA or GEO