4.Yagnopa veetha dharana manthra
After bath again change poonal by reciting manthra as given in s.No.1.Please note that now a days very rarely people take bath after mahaa sankalpam but do prokshana snanam i.e bath by sprikling of water on the head.
5.Kanda Rishi Tharpanam
4.Mamo partha samastha durida kshya dwara sri parameshwata preethyartham sravanyaam pournamaasyam adhyoyapakrama karmangam kanda rishi tharpanam karishye.
Wear poonal as garland and do tharpanam using water mixed with thil (black gingely) and akshatha
Each manthra has to be chanted thrice and tharpanam done.
1.Prajapathim kanda rishim tharpayami
2,Somam kanda rishim tharpayami
3.Agnim kanda rishim tharpayami
4.Viswaan devaan kanda rishim tharpayaami
5.Saahinkeer devatha upanishadha tharpayami
6.Yagnigeer devatha upanishadha tharpayaami
7.Vaaruneer devatha upanishadha tharpayami
8.Brhamanagum swayubhuvam tharpayaami
wear poonal in the normal fashion and then do aachamana.
Summary meaning:Tharpanam means really satisfying.By this tharpanam we satisfy the rishi(sages) of Soma(moon), Agni(fire), Viswaan devan(all gods looking after earth), etc.
Though these are essential part of Avani avittam , I am not giving this because Vedic manthraas are very diffcult to transliterate in to English and reading them wrongly would be counter productive.