OK. I think this is where you are going wrong. It is a little fiddly, so this is not unusual. After your tMap_1, you need to add a tFlowToIterate. This will create an iteration after this component. The tFlowToIterate temporarily stores the row data into the globalMap using the key {row}.{column}. So a column called "myValue" coming out of your tMap would have the key "out1.myValue". Keep this in mind.
The next thing you need to do is connect a tJava to your iterate link. This is a dummy component. Do nothing with this. Simply connect it to the tRestClient using the OnComponentOK link. Now, your tRestClient looks OK apart from the query parameters. You need to ensure the names are precisely as your web service API has listed them. Your values need to be the globalMap variables explained in the first paragraph. So if your API has a variable name of "variable1" and you want to pass the value of "myValue" to it, you would add the following in the query parameters section....
Name: "variable1"
Value: ((String)globalMap.get("out1.myValue"))
The above assumes that "myValue" is a String....hence the (String) before the globalMap
