Website seo h1 tag?

I want to add an <h1> tag to my website to help with my SEO, I have my hosting with Weebly, my website name is www.tropicarehomeinspections.com

With Weebly I have the option to add an HTML section, I made a test header with the h1 tag and it did work the problem is the text was very large and the text color was a light gray, I want a smaller text a little bit bigger then the standard font on my website and in black, I am not sure what I can do to make the change. Can someone help me out with the coding or give me an idea on what I need to write code wise to make the changes for black font and a bit smaller size. Thank you in advance for the help and info.