Trend graph required on day wise

I have a posting date & posted amount of payment in one BI table. I do have the timestamp of this event in Event log table… is there any solution ? I want to create a graph of days (31 days) day wise payment received by customer… to be more specific,
I need a chart like below image

But i have the data in only BI table & timestamp in event log table… Not able to add both because schema is not allowing to add the days with trend line… can some one guide ?