I can give a brief intro to the Tibetan alphabet. Here an acute accent mark ʹ indicates high tone, and a grave accent mark ` indicates low tone. The first consonants of the first five rows are unaspirated and have high tone. The second consonants of the first five rows are strongly aspirated and have high tone. The third consonants of the first five rows are moderately aspirated and have low tone.
ཀ་ ཁ་ ག་ ང་gá khá kà ngà
ཅ་ ཆ་ ཇ་ ཉ་ já chá cà nyà
ཏ་ ཐ་ ད་ ན་ dá thá tà nà
པ་ ཕ་ བ་ མ་bá phá pà mà
ཙ་ ཚ་ ཛ་ ཝ་dzá tshá tsà wà
ཞ་ ཟ་ འ་ ཡ་ shà sà à yà
ར་ ལ་ ཤ་ ས་ rà là shá sá
ཧ་ ཨ་há á
The vowels i, e, and o are written as marks above ཨ་ or a consonant, and u is written as a mark below ཨ་ or a consonant:
ཨི་ ཨུ་ ཨེ་ ཨོ་ i u e o
The vowel sounds ä, ö and ü also exist, but they do not have separate written forms.
Tibetan spelling is extremely complicated due to its very old orthography. One word may be spelled the same way throughout all the Tibetan regions but pronounced very differently according to the language/dialect of the speaker. This means that in Standard Central Tibetan, words are seldom spelled exactly as they sound. There are consonant clusters, prefixes, suffixes, superscribed letters and subscribed letters that can affect aspects of pronunciation like tone and aspiration or may not be pronounced at all. I was extremely intimidated by all this when I first began studying Tibetan, but unfortunately there are almost as many systems of phonetic transcription for Tibetan as there are resources for studying Tibetan. Once you learn some of the rules regarding sound changes, it's actually not as terrible as it might sound