Hi @vickyregi, welcome to the KNIME forum
To have a look at a decision tree example with a binary/classification target you could try this example and swap the data and possibly the algorithm:
For a more extensive discussion about predicting numbers I have recently collected some entries.
Since this is an assignment you might want to think about your own research and contribution into this
Then one general remark. It is not so easy to predict numbers like unemployment rate or GDP just from a time series since a myriad of factors would play into that - economists and others are constantly struggling to do this.
Cf. also this debate with a example for GDP figures: