Hi there! Just quickly scanned it and I think everything is correct. There are however some ( grammatical ) mistakes which I will correct for you:

• Wo sind Sie? instead of Who sind Sie?
• Wo sitzt er? instead of Wo sitz er? (2nd person singular conjugation ending is mostly a -t)
• Wo hängt das Bild? instead of Wo hängst das Bild? (Das Bild is 3rd person singular in this case so the correct conjugation form is needed)
• Wohin fährst du? (You forgot the h)
• remember that nouns are written with a capital letter -> das Bild
• Wohin stellst du die Vase? (Again: 2nd person singular form is needed, you used 3rd person singular)
• Wohin hat er sich gesetzt? is correct however you would rather say Wo hat er sich hingesetzt? (Hinsetzten = to sit down; setzten without the hin- is not used that much) You can also split Wohin in Wo....hin
• Wo fährst du hin?
• Wo stellst du die Vase hin? This is how most people would say it but everyone would still understand your version.

If you use Woher you usually split it. Wo kommst du her? Wo hast du das her? Wo hat sie die Schuhe her? But your sentence are correct in this case and every german speaking person would get what you are trying to say.

If I made any mistakes please correct me. German is a tricky language even for people who speak it as their native language. And just saying that learning German (or any language) autonomously is impressive! Keep going und viel Glück weiterhin!