Same way you say it in English only you use a spanish tongue.
To say "I only speak French" in Spanish, you can say "Solo hablo francés."
Único or Única
There is only one way to say hello in Spanish: hola.
There is no way to say Ashton in spanish. if you go to a spanish speaking country and ask they'll say your name the way you did only in an acsent.
You translate "You are my only desire" to Spanish it becomes Eres mi único deseo.
"Si tan sólo..."
nomas uno
solo uno
I wouldn't what? You can't say I wouldn't in Spanish because (for example) "I wouldn't eat" would only be one word in Spanish: "Comeria"
you say it the same way only we say it with a little acsent like when i say it in spanish it sounds weird to me but i know what it means
You can say "Sólo hablo español hoy"