BLOG DESIGN AND LAYOUT

I am currently playing about with the design and layout of my blog presently,  actually I have little idea what I am doing (!), so apologies for any convenience or confusion that may arise in the interim! Bear with me.
And of course feel free to comment if you wish.
Right now it all seems too hard so I am going to go out for a coffee and to buy some spring onions and pumpkin seeds needed for tonight's dinner.
PS For the life of me I can't see how to change the font size. Anyone using Blogger out there able to help me?