Is it possible to add metadata to a Wordpress site without a Plugin?

[Lora Elyse Photography]

Hello,

I am a complete beginner in SEO and I have downloaded SEO Quake to diagnose the different sections on my site to see how search engine friendly they are. Turns out not at all friendly and I need to add metadata.
I can't install a plugin without a friend who hosts my website, and he's taking a while to get back to me about the plugin - so is there a way to add metadata without installing a plugin? There is also a section on SEO Quake about headers H1, H2... all the way to H6. Most of those only have 1/2 underneath and it's mainly is the H2/H3 sections. How do I add more header tags with my keywords?
Please helllllpppp I need to get my website boosted so that people can see my work and commission me!
Thanks you Jake and Harunar for your answers, I really appreciate it. I think the hosting platform is restricted because i am unable to log in myself. He has to 'sort it out' for me basically... I'll wait for him to get back to me!

Thank you again!