The easiest is to first prepare stock solution for each component: we usually do 1M Tris-HCl pH7.4 and 5M NaCl. From those, mixing 3/4 of the former and 1/100 of the latter and adjust the volume with water will give you the buffer. BTW, 750mM is a very concentrated Tris buffer...
Thank you Katja Härtl and Mehdi Roshdi Maleki , it also very useful for me.
So, Dear Ghanshyam Jangir After calculate the different necessary masse, of each reagent as Katja Härtl said just mix them as Mehdi Roshdi Maleki said.
BTW, can I use the same way to prepare 50 mM Tris (8.0), 10 mM EDTA, 100 µg/mL RNAse ?