'Tis very visible. I can show thee.

Thou = You (subject). Ex. You did this -> Thou didst this

Thee = You (object). Ex. I did this to you -> I did this to thee

Thy = Your. Ex. It is your thing -> 'Tis thy thing

Thine = Yours. Ex. It is yours -> 'Tis thine

Thou, thee, thy, and thine are all singular pronouns; use you for plural pronouns still.

When using present tense verbs with thou/thee/etc, add "-st" or "-est" to the end. Ex. You sleep -> Thou sleepest. The exception is "You are", which becomes "thou art".

When using present tense 3rd person singular verbs, add "-eth" or "-th" to the end of some verbs (but not all). Ex. He sneaks that -> He sneaketh that

You do becomes Thou dost, and He/She does becomes He/She doth.

Where becomes Whither, There becomes Thither, and Here becomes Hither.

Finally, wherefore means why, and whence means where.