Search for your dataset, assign samples to groups, and then you can analyze everything with just a few mouse clicks.
Once you get familiar with the basics of RNAseq, then download the raw FASTQ files and analyze it yourself. Until then, stick with tools that do everything for you and that have a nice user-friendly interface.
If you learn visually then here is one set of tutorials. Look at the link in description to download example data/slides etc. There are many other tutorials available on YouTube. Quality is going to vary so decide for yourself.