How to edit custom newform.aspx?

Hi,

Basically I'm new in sharepoint. I believe this is a common question but i didin't manage to find a solution suitable for me.

I want to edit the form for adding new items to the list. When i click on edit form in sharepoint designer 2010 I get this code:

<WebPartPages:ListFormWebPart runat="server" __MarkupType="xmlmarkup" WebPart="true" __WebPartId="{0BB26BD1-11EA-4326-AFC0-FA5C28915091}" >
<WebPart xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://schemas.microsoft.com/WebPart/v2">
  <FrameType>Default</FrameType>
  <Description />
  <IsIncluded>true</IsIncluded>
  <PartOrder>2</PartOrder>
  <FrameState>Normal</FrameState>
  <Height />
  <Width />
  <AllowRemove>true</AllowRemove>
  <AllowZoneChange>true</AllowZoneChange>
  <AllowMinimize>true</AllowMinimize>
  <AllowConnect>true</AllowConnect>
  <AllowEdit>true</AllowEdit>
  <AllowHide>true</AllowHide>
  <IsVisible>true</IsVisible>
  <DetailLink />
  <HelpLink />
  <HelpMode>Modeless</HelpMode>
  <Dir>Default</Dir>
  <PartImageSmall />
  <MissingAssembly>Err</MissingAssembly>
  <PartImageLarge />
  <IsIncludedFilter />
  <ExportControlledProperties>true</ExportControlledProperties>
  <ConnectionID>00000000-0000-0000-0000-000000000000</ConnectionID>
  <ID>g_3f024e74_0941_4b63_99b3_c33b21df7c70</ID>
  <ListName xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">{F7CD289E-B836-440C-9AAE-1DBD783CD235}</ListName>
  <ListId xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">f7cd289e-b836-440c-9aae-1dbd783cd235</ListId>
  <PageType xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">PAGE_NEWFORM</PageType>
  <FormType xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">8</FormType>
  <ControlMode xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">New</ControlMode>
  <ViewFlag xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">1048576</ViewFlag>
  <ViewFlags xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">Default</ViewFlags>
  <ListItemId xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">0</ListItemId>
  <TemplateName xmlns="http://schemas.microsoft.com/WebPart/v2/ListForm">ListForm</TemplateName>
</WebPart>
</WebPartPages:ListFormWebPart>

The actual form looks much more different in the browser:

How can I delve to the form to be able to edit it?

Sorry for my English, thanks in advance.