Step 1 - who originally formed the company in order to sell the shares and a) why do they want to sell them to you? And how much would they sell the share for?
Step 2 - if training is being done at cost, how does the company make a profit?
Step 3 - how can that be guaranteed; it would depend on the number of students surely?
Step 4 - legal partner or shareholder? The two are different. A shareholder does not have any right to a dividend. If a partnership, then each partner is jointly and severally liable for the debts of the business as well.
Step 5 - if it's a private company company or partnership, you will need the other shareholders' permissions to sell. What if they don't like your new shareolder? You cannot publicly trade shares in private companies.
Haven't really thought this through, have you?
And I haven't even started on the tax and stamp duty implcations.
Cheers
Whirls