Mon Ttravail

No need to capitalize every word of a title in French

Aujourd'hui, je vais travailler àau bureau/dans ma boîte.

"boîte" is somehow colloquial in the sense of "entreprise", and would heavily imply you own the company
"au bureau" would be a far, far better pick

C'Nous sommest très occupés en ce moment, parce que c'est presque la saison des impôts.

A place is "occupée" when people inhabit it
Only people can be "occupés" when they have work to do

Pour le plus parGlobalement, j'aime bien mon travail.

The word would be "la plupart", but would sound like a literal translation of the English "for the most part"
"For the most part" in this sense would translate as "globalement" or "dans l'ensemble"

Ça peuxt être intéressant, mais aussi ennuyeux parfois.

-x never ever is a third person singular ending in the indicative

Je travaille avec des investissements.

"avec" would really emphasize the facts investments are your working tools
"DANS les investissements" would emphasize it's your sector, your field (I felt like you rather meant the latter)

La partie la plus intéressante de mon travail est quand j'achète et vends en bBourse.

"Bourse" is capitalized when it means "stock exchange"
"bourse" means "(scholarship) grant", it's also a somewhat old word for "purse"