How do you spell your the best in french?

There's no direct translation for "your the best" in French. You'd need to rephrase it based on the context:

If you're saying someone is the best:

* Tu es le/la meilleur(e). (You are the best.)

* Tu es excellent(e). (You are excellent.)

* Tu es formidable. (You are amazing.)

* Tu es génial(e). (You are awesome.)

If you're thanking someone for being the best:

* Merci d'être le/la meilleur(e). (Thank you for being the best.)

* Tu es vraiment le/la meilleur(e). (You are truly the best.)

If you're telling someone they're your best friend:

* Tu es mon/ma meilleur(e) ami(e). (You are my best friend.)

Remember to use "le" for a male, "la" for a female, and "le/la" when you're not sure of the gender.