# defining constants and plotting them

I want to plot some functions and define some variables as constants, apparently the variables are not being recognized as constants. I'm kinda new to coding so this is very difficult to me. this is my code.

Ca = Ca0 E^(- \[Xi] t), t, Constants -> {Ca0, \[Xi]};

Cb = Ca0 (\[Xi]/(\[Eta] - \[Xi])) (
E^(-\[Xi] t) - E^(-\[Eta] t)), t, Constants -> {Ca0, \[Xi], \[Eta]};
Cp = Ca0  (1 +
1/(\[Eta] - \[Xi]) (-\[Eta] E^(-\[Xi]  t) + \[Xi] E^(-\[Eta] \
t))), t, Constants -> {Ca0, \[Xi], \[Eta]};
Plot[{Ca, Cb, Cp}, {t, 0, 10}]


You must establish a value, or at least a range of values, for the constants

Ca = Ca0 E^(-\[Xi] t);
Cb = Ca0 (\[Xi]/(\[Eta] - \[Xi])) (E^(-\[Xi] t) - E^(-\[Eta] t));
Cp = Ca0 (1 +
1/(\[Eta] - \[Xi]) (-\[Eta] E^(-\[Xi] t) + \[Xi] E^(-\[Eta] t)));

Plot[{Ca, Cb, Cp} /. {Ca0 -> 1, \[Xi] -> 1, \[Eta] -> 2}, {t, 0, 10}]

Manipulate[
Plot[{Ca, Cb,
Cp} /. {Ca0 -> Subscript[Ca0, 2], \[Xi] ->
Subscript[\[Xi], 2], \[Eta] -> Subscript[\[Eta], 2]}, {t, 0,
10}], {{Subscript[Ca0, 2], 2}, 0, 10}, {{Subscript[\[Xi], 2], 1},
0, 10}, {{Subscript[\[Eta], 2], 2}, 0, 10}]