Garson seems to be right (though I never have learned grammar by heart and don't want to look in to it now), but you have made a lot of mistakes in your post (though you are quite good in general), hope you don't mind if I correct them:
Sveiks...vai varat man palīdzēt?
Sveiks is masculine singular,
varat is plural, you can use bout in singular as II person plural is polite form, however you shouldn't use both plural and singular when talking about same object. Singular II person for
varēt is
vari and plural for
Sveiks is
Sveiki, mind that
Sveiki is gender neutral and used more often, it is somewhat semi-formal greeting
Es ltietoju grāmatu “Colloquial Latvian“ mācīties latviešu valodu.
mācīties is infinitive, you would use infinitife (I use book X to learn) in English, but in Latvian it is just as if you were saying just "learn" (I use book X learn) in English, you should say
lai mācītos (in order to learn) or
mācoties (while learning). As you can see this would sound a bit awkward, so it would be better if you emphised learning in this sentence and put it at begining of the sentence , like
Es mācos latviešu valodu no grāmatas X (I learn Latvian from book X)
Līdz šim visu saprotu sapratu bet sestajā lekcijā ar virsrakstu nosaukumu “Dzimšanas diena“.
Everything that happened before now should be in past if you're using simple tense, virsrakstu isn't entirely wrong, but it is better style to say
ar nosaukumu (with name).
Virsraksts mostly refers to a newspaper headline or title of an essay, not to chapters in a book
Vispirms ir teikums “Laiks ir pēkšņi mainījies“ (domāju tulkots ir tiek “The weather is suddenly changing“, vai šis tā ir pareizsi.?) Nu, es zinu šo vārdu no darbības vārdua “Mainīties“ bet kāds ir mainījies.? Vai šis ir darāmās kārtas pagātnes divdabis?
Use
tiek (passive) instead of
ir when you are talking about something being done (it means roughly "is being"). When asking if it is correct you should ask if
it is correct that way not if
it is correct, so you should use
pareizi (I think it is adverb, while pareizs is adjective, but I could be terribly wrong about this).
No usualy is followed by genative (except in some expresions whith
no.. līdz... ).
Atkart, teikums “Vejš ir sacēlies“ (The wind is starting?). Atkal es zinu šo no darbības vārdu “Sakt“, tādēļ tāpat jautāums.
There is no such word "atkart", can't imagine what you posibly meant.
Sa- is a prefix, the verb is
celt not
sākt, it does mean that wind started to blow, but normaly these two words have totaly different meaning.
Sacelties means to rise (sudenly) or to revolt,
celt is to lift, to build - nothing to do with starting
Beidzot simt
astoņā astotajā lapā ir vārds “tiem“ . Ko
šis tas nozīmē.? Es nevaru atrast tulkojumu. Bija lietots frāzē “Apstakļi tiem... “
Ļoti pateicos..!
Nummeral is
astoņi, but you count pages with ordinals, ordinal is
astotais.
Šis means "this'',
tas means ''that'' or ''it'', it sounds better to use
tas.
Apstākļi tiem (it means "to/for them") is wierd phrase for discussing weather, BTW (though - what has weather to do with Birthday ?), apstākļi means circumstances, hower in this case it could mean weather conditions...