How do I get to form mode?

There is no "forms mode" per se when using TurboTax Online.  However, you can...

To preview your 1040 form before filing, follow these steps:

1. Sign in (continue) your online return, if you're not already signed in.
2. Select My Account near the top of your screen, and then Tools from the drop-down menu.
3. Under Other helpful links... click View Tax Summary.
4. Select Preview my 1040 near the top of your screen.
5. Click Back near the top of your screen to exit the preview screen.

To preview all forms, schedules, and worksheets in your return before filing:

1. From the My Account drop-down at the top, select Print Center.
2. In the pop-up, click the first option (Print, save, or preview this year's return). If you haven't paid or registered yet, you'll be prompted to do so before you can view your full return.

What should i do if i'm using turbo tax online.

@QS01 

If you absolutely need forms mode, your only option is to switch to a desktop version of TurboTax.

https://ttlc.intuit.com/turbotax-support/en-us/help-article/intuit-product-orders/switch-turbotax-online-turbotax-cd-download/L8oxEJNu5_US_en_US

You have added on to a very old post.  What is your question?  

My question is i'm using Turbo Tax online to file my return but there is no option related to other income.