You can use the Latin phrase "Mundus tuus est". But since Latin doesn't have "the", you can lean towards "hic mundus tuus est", meaning "this world is yours".
The ancient Latin alphabet (Abecedarium Latinae) only contained 21 letters during the period of Cicero (106-43 BC) . During classical period, the letter "i" diverged into vowel "i" and consonant "j"; "v" became "u" and "v"; two letters - y and z- were brought into Latin during the middle ages. "W" is only used in recent biological literature, for spelling foreign names.
The Latin written today thus includes 26 letters (which also make up the English alphabet), there are 6 vowels: a,e,i(y),o,u and 20 consonants: b,c,d,f,g,h,j,k,l,m,n,p,q,r,s,t,v,w,x,z. Note that during the classical times, all letters were written capitalized.
The Latin alphabet was meant to be entirely phonetic. Unlike us, the ancient Romans did not inherit their spellings from any earlier language. What you see is what you get.
Language teaching was big business in Roman times, and ancient Roman grammarians give us surprisingly detailed information about the sounds of the language.
Languages derived from Latin give us a lot of evidence. In fact, many of the letters of the alphabet are pronounced the same way in French, Spanish, Portuguese, and Italian. It stands to reason that the original Latin pronunciation has survived.
Spelling errors made by the ancient Romans are very informative. If two letters are often mixed up, they must sound fairly similar. Likewise, if two letters are never mixed up, we know they sounded different.
Here’s an example. In classical times, the natives had no trouble keeping ae distinct frome; if they ever misspelled ae it came out ai. Later on, they started changing ae to e. That enables us to pinpoint when the sound of ae changed.
Finally, transcriptions into other writing systems, such as Greek and Sanskrit, often pin down the ancient pronunciation of Latin very precisely.
Learn more about Latin language from sources below:
la.raycui.com - The Latin alphabet
www.orbilat.com - The Pronunciation of Classical Latin
www.covingtoninnovations.com - Latin Pronunciation Demystified
www.omniglot.com - Latin language (Lingua Latina)