Don't placeholder
For similar reasons to the above note about editing: please don't post a 'placeholder' or 'TBD' post with a roll and then go back and fill it in based on the result. This is a common practice in many games and it is possible that it works in DnD and it's mechanical ilk, but more fiction oriented games like this work better if you have the Fiction First.
Post what you are trying to do --up to the point it could fail-- along with the setup for any roll you are trying for.
Drop a post in the OOC thread saying what your intent is --in clear out-of-character language.
Include the Attribute you think you should roll with --and why if it is unclear (see
Rules -> Rolling the Dice). That way the GM can more easily spot a mismatch in your intentions or understanding of the rules or the situation. The GM will decide (and explain) the actual possible rolls and outcomes, which can then be discussed if needed. All players should feel free to weigh in on such things, the GM has 'final say' not the only say.
You can then go back and edit the post to add the roll. Based on the outcome you may be free to immediately continue the action in a
new post (see 'Don't Edit'), or you may need input from the GM before continuing, in which case, mention in the OOC that you have rolled.
Regularly you will have to go back and add a roll, the GM will point out that "It looks like you are trying to (insert Action here). Is that correct? If so then roll for it." This will become clear as we play.
When you roll: Include a descriptor of what you are doing in the Reason field.