I'm assuming you have a qualified employee stock purchase plan (ESPP) and sell immediately after receiving the shares, which means you have what's called a disqualifying disposition. Selling only $1000 worth actually complicates things, so let's instead first assume you sell all shares. What should happen is the W-2 from your employer will report the discount of $176, which will be taxed like regular income. If it doesn't, you need to add it as miscellaneous income to your tax return (but not subject to self-employment tax). You will receive a 1099-B from your brokerage showing your proceeds of ~$1176 minus fees. The cost basis should be reported as $1176, although often it will show as $1000, in which case you need to manually adjust it to avoid being double-taxed. So overall, you will have a small short-term capital gain or loss (taxed at regular income rates), then the discount which is also taxed like regular income.
If you instead only sell $1000 worth (100 shares instead of all ~117), your discount, proceeds, and cost basis will all be proportionally less. Again, since you're selling immediately, the main effect is you only pay regular income tax on the discount, in this case ~$150 instead of the full $176.
If you were to hold on to the shares for longer before selling, you could get long-term capital gains tax rates, and longer still you could get a qualifying disposition, which potentially have more favorable tax treatment. It's complicated so I won't go into the details, but you can find them elsewhere. However, it's often advised to sell ESPP shares immediately and treat the discount as a cash bonus, since your income is already somewhat tied to your employer's performance.
